1976 20hp evinrude, misfire & coil hits flywheel

ticci

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Jun 28, 2020
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Hello all and first let me apology, I know these has been discussed times before. I recently got an old 20hp evinrude engine (206B62E) which should have been in working order. Got it running yesterday and found out that the engine would misfire on low rpms and run good on full throttle.

Took flywheel of to inspect points etc and found that the timing plate was loose to axle and one of the 4 coil ends had taken a small hit. Put some thick grease on axle and put the thing back together and it run good on idle and worse on rpm's.

So I supposed that the problem was slack between magneto plate and axle, but here was suggested that the problem was armature plate support and could be fixed with punching the plate? I have no experience with outboards and somehow struggle to understand how this thing works. I can get new sleeved machined to the magneto plate, would these be better option?

Cant find any info of this engine online other than the model year but i would suppose this is quote similiar to 25hp engines?

I'll try to attach some pictures later on, would appreciate your answers.
 

racerone

Supreme Mariner
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Dec 28, 2013
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36,043
Post pictures of the magneto.----Is this a Canadian built / marketed motor ?
 

racerone

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Dec 28, 2013
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Move the coils so that flywheel does not hit.-----I knew there was something odd about the model # listed.
 

ticci

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Jun 28, 2020
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7
What about the play on the magneto plate? Doesn't that affect ignition timing?
 

oldboat1

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Flip the armature plate support over (second pic). Flat side up.
 

racerone

Supreme Mariner
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Your location ?-----If magneto plate bushing is loose a good used plate is an option.----Might not be that hard to find.
 

ticci

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Jun 28, 2020
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Thanks to all for your answers! Okay, dug a little deeper into the engine.

Looking this picture: https://www.*****************/parts/j...6amp%3B+Piston

Removed armature plate support (#10) to reveal retaining ring (#12) and inspect the wear. Found out that retaining ring was installed flat side up, although looking the pictures it should be coned side up? Flipped the plate and put evrything back together - took the side by side action pretty much out but I ended up with horrendeus up and down play! Now flywheel magnets pick up the magneto plate by some 1/4 inches when turning the engine.

Flip the armature plate support over (second pic). Flat side up.

Are you referring to the armature support plate (#10 on picture, the brass bracket hold by 3 screws) or the retaining ring (#12, where you fasten the magneto plate on) underneath it, which was already flat side up?
 
Last edited:

ticci

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Jun 28, 2020
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Here's the link, hopefully this works.

Edit: well anyways, marineengine site > Evinrude > 1972 > 20hp > pick model > crank and piston. Part numbers for #10 303278 and #12 303277.
 

racerone

Supreme Mariner
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Dec 28, 2013
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Nope----That ring with the 4 screw holes should be FLAT SIDE facing up !!!
 

ticci

Cadet
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Jun 28, 2020
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D'oh. So is the only problem worn brass bushing in the middle of the magneto plate and replacing it or whole plate should fix these problems?
 

ticci

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Jun 28, 2020
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7
Well let me ask it differently. I'd say the problem I have is the loose fitting of the magneto plate which causes the timing to change and coil to hit flywheel. Is there anything else that affects the centering of the magneto plate than the brass fitting in middle of the plate?
 
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